Alex building an eyewall, still not a hurricane

By: Dr. Jeff Masters , 7:34 PM GMT on June 29, 2010

Share this Blog
3
+

Tropical Storm Alex is slowly building an eyewall, which is now more than 50% complete, according to recent satellite imagery and microwave images (Figure 1.) Satellite loops show a slot of dry air is spiraling into the center of the storm, and until this dry slot gets closed off, Alex will not be able to intensify significantly. Alex's heavy thunderstorms and low level spiral bands continue to slowly increase, but upper-level outflow is mediocre to the north and east, and absent elsewhere. The Hurricane Hunters are in the storm and have not found any hurricane-force winds at the surface yet.


Figure 1. Microwave "radar in space" image taken at 10:11 am CDT Tuesday June 28, 2010, showing that Alex had built an eyewall a little more than 50% complete. Image credit: Navy Research Lab.

Impacts
Alex is already bringing bands of heavy rain to the coasts of Texas and Mexico, as seen on the Brownsville, Texas radar. Hurricane local statements with projections for how Alex will affect the coast are now being issued by the National Weather Service in Brownsville and Corpus Christi. Since Alex is a large storm, it will have a storm surge that will affect most of the South Texas coast. NHC is giving a 40% - 60% chance of a storm surge of at least 3 feet affecting the Brownsville area, and 10% - 30% chance the surge will exceed 5 feet. In theory, a Category 2 hurricane moving WNW at 5 mph can bring a storm surge of up to 8 - 9 feet to the South Texas coast (Figure 2.) However, Alex is now unlikely to get that strong, and the surge should be less. Flooding damage from the expected 6 - 12 inches of rain from Alex will also be a major concern, as will wind damage. The combined wind, surge, and flooding damage from 2008's Hurricane Dolly, which hit near Brownsville, were about $1.05 billion. Dolly was a Category 2 hurricane offshore that weakened to a Category 1 hurricane with 85 mph winds when it made landfall. I expect Alex will be similar in its impacts to Dolly, though Alex's storm surge damage is likely to be greater. If Alex hits more than 50 miles south of the Texas border, as currently appears likely, the damage will be far less, since this region of the coast is relatively sparsely populated.


Figure 2. Maximum Water Depth (storm tide minus the elevation of the land it is passing over) computed using the primary computer model used by the National Hurricane Center (NHC) to forecast storm surge--the Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model. The accuracy of the SLOSH model is advertised as plus or minus 20%. The "Maximum Water Depth" image shows the water depth at each grid cell of the SLOSH domain. Thus, if you are inland at an elevation of five feet above mean sea level, and the combined storm surge and tide (the "storm tide") is ten feet at your location, the water depth image will show five feet of inundation. This Maximum of the "Maximum Envelope of Waters" (MOM) image was generated for high tide, and thus shows the worst-case inundation scenarios for a mid-strength Category 2 hurricane moving WNW at 5 mph. For more information on storm surge, consult our detailed storm surge pages.

Track forecast for Alex
The latest 12 UTC (7am CDT) runs of our most reliable computer models confirm the faster movement of Alex to the coast, and residents in the affected areas now have 12 hours less to prepare for Alex's arrival than it seemed with yesterday's forecasts. Conditions will begin to deteriorate along the coast late tonight, so today is the day to finish preparations if you live near the Texas/Mexico border! The ridge that is steering Alex to the northwest is expected to strengthen today and Wednesday, which should push Alex on a more west-northwest and then westerly track on Wednesday. A few models even have Alex moving west-southwest by the time it makes landfall. The most northerly landfall location, near Brownsville, is predicted by the HWRF model.

To get the probability of receiving tropical storm force winds or hurricane force winds for your location, I recommend the NHC wind probability forecasts. The 4am CDT (9 UTC) wind probability product predicted that Brownsville, Texas had the highest odds of getting a direct hit from Alex:

Brownsville, TX: 88% chance of tropical storm conditions (winds 39+ mph), 23% chance of hurricane force winds (74+ mph). This is the cumulative probability through Saturday morning. The wind probability forecasts also include separate probabilities for each 12-hour period between now and three days from now, and each 24 hours for the period 4 - 5 days from now.

Corpus Christi, TX: 42% tropical storm, 1% hurricane.

La Pesco, MX: 37% tropical storm, 3% hurricane.

Freeport, TX: 18% tropical storm, 0% hurricane.

Tampico, MX: 14% tropical storm, 0% hurricane.

Galveston, TX: 13% tropical storm, 0% hurricane.

Intensity forecast for Alex
Alex is over a region of ocean with a warm, clockwise rotating Loop Current eddy that broke off from the Loop Current in July 2009 and moved west-southwest over the past 11 months. This eddy has moderately high total ocean heat content . Wind shear has fallen to a low 5 knots, and is projected by the SHIPS model to remain in the low range, below 10 knots, this afternoon and Wednesday. The combination of low wind shear and moderately high ocean heat content should allow Alex to intensify into a Category 1 hurricane, but time is running out for it to be a Category 2 hurricane. NHC is giving Alex a 79% chance of being a hurricane on Wednesday morning, and a 4% chance it will be a major hurricane at that time. Water vapor satellite images show the amount of dry air over the western Gulf of Mexico has decreased over the past day, though as I noted above, the dry slot wrapping into Alex's core is currently keeping the storm from closing off an eyewall. Dry air may turn out to be an increasing detriment to Alex on Wednesday as the storm approaches land. Another factor limiting Alex's intensification may be that the atmosphere is more stable than usual right now--temperatures at 200 mb are a rather warm -50°C, and are expected to warm an additional 1 - 2 degrees by Wednesday. I don't expect Alex to stall out again, so slow motion leading to upwelling of cold water will probably not be a problem for Alex. The main issue limiting intensification will be the fact that Alex is so large, and it takes more time for a large storm to organize. Thus, I think Alex has only a 10% chance of intensifying into a major hurricane before landfall.

Elsewhere in the tropics
The last few runs of the NOGAPS model have been predicting the formation of a tropical disturbance off the coast of Nicaragua on Friday or Saturday that will move northwestward towards western Cuba. The GFS model, and the two models that use it for starting conditions, the GFDL and HWRF, are indicating the possibility that a weak extratropical storm may form along coastal Alabama this weekend. It is unlikely that such a storm would be over water long enough to transition to a tropical storm.

Wind and ocean current forecast for the BP oil disaster
It currently appears that Alex's winds will not directly affect the oil slick location. However, because Alex is such a deep low pressure region, strong southeast to south winds of 10 - 20 knots will blow over the oil slick region today through Thursday, according to the latest marine forecast from NOAA. The resulting currents should act to push oil to the west and northwest onto portions of the Louisiana, Mississippi, and Alabama coasts, according to the latest trajectory forecasts from NOAA and the State of Louisiana. Oil will also move westward along the central Louisiana coast towards the Texas border. Alex is currently bringing swells of 3 - 4 feet to the coastal regions impacted by the oil slick, and these swells will increase to 6 - 8 feet on Wednesday. Wave heights will increase to 5 - 7 feet on Wednesday. Alex is expected to bring a storm surge of 1 - 2 feet along the coast in the oil spill region. The swells and waves that will accompany these high water levels will act to push oil deep into the marshlands in some locations. The long range forecast for the oil slick region is uncertain, due to the possibility a weak area of low pressure might develop late this week along the remains of a cold front draped across the region.

Resources for the BP oil disaster
Map of oil spill location from the NOAA Satellite Services Division
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

"Hurricane Haven" airing again this afternoon
Tune into another airing of my live Internet radio show, "Hurricane Haven", at 4pm EDT today. Listeners will be able to call in and ask questions. The call in number is 415-983-2634, or you can post a question in the comments area on my blog during the show. You can also email the questions to me today before the show: jmasters@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line. Some topics I'll cover today on the show:

1) Alex
2) A look ahead at what may happen the rest of hurricane season

Today's show will be about 45 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.

Next post
I'll have an update Wednesday morning by 9:30am CDT. Rob Carver is planning on doing a late-night update tonight.

Jeff Masters

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 443 - 393

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40Blog Index

Entering just to remove any sharp objects then back to lurking. Many sharp tongues here.
Member Since: Posts: Comments:
Poll! What do you think Alex will become?

A. Stay at Tropical Storm

B. Cat 1 Hurricane

C. Cat 2 Hurricane

D. Major Hurricane
Member Since: Posts: Comments:
.."Crow Mignon"..?
Member Since: July 3, 2005 Posts: 427 Comments: 129439
I was in some, errr, less than savory parts of town)

we prolly went to some of the same places then :)
Member Since: Posts: Comments:
I agree hurrkat, that is why I am still lurking. the fat lady has not even warmed up yet. I will believe he is done when he reaches land and see Jim Cantore getting soaked! LOL
Member Since: Posts: Comments:
Quoting Ossqss:


I was thinking of a different word and I think I spelled it wrong :)

Crow-Magnon


I must say that your mis-spelling is very apropos
Member Since: Posts: Comments:
Quoting LloydBentsen:

Forgive my ignorance, but what altitude is water vapor measured? Or is it across all altitudes?
All altitudes basically.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Still a TS? Wow. Looks pretty, though.
Member Since: Posts: Comments:
Quoting reedzone:


Ahemm.. I'm 21, songwriter, in college... I've got off the deep end in past years on this blog but was never banned, I know when to keep my cool which is why I deleted that one post earlier this afternoon.


I have no gripe with you. However occasionally I have the feeling that someone did not put the screen in the window right and a misquitoe got in.
Member Since: Posts: Comments:
Quoting Floodman:


Oh no! Wrong time of year for chicken dances...that simply excites the weather gods and INCREASES the problem
Oh my! Ixna on the ancda then....
Member Since: Posts: Comments:
Quoting StSimonsIslandGAGuy:
Thanks 1900hurricane, savannahstorm, and 47n91w :) When I thought about Cat 3 being a major, the others just popped into place!

So the complete list:

Cat 1 Lieutanant
Cat 2 Captain
Cat 3 Major
Cat 4 Colonel
Cat 5 General


I just thought of this, what about depressions and storms, and maybe even invests? XD
Member Since: Posts: Comments:
Eye of Alex appearing.. I suspect we'll have a hurricane in a few hours.

Member Since: Posts: Comments:
Quoting tkeith:
there must not be many Matamoras bloggers...

BTW...anyone know what the population is there?

I haven't been there since the 80's but I remember there being alot of people living there.


About 425,000 per the 2005 head count...oddly, presslord and I were just talking about Matamoras earlier...seems all of us were there in the 80s. Interesting town and even then a great advertisement for kevlar underwear (I was in some, errr, less than savory parts of town)
Member Since: Posts: Comments:
425. xcool
lmao
Member Since: Posts: Comments:
nope, I never said the word chicken dance LOL

I said some call Africa and tell them to not send any "waves" untill Jeff gets back from vacation.
Member Since: Posts: Comments:
SSIGG...TS= sargent?
Member Since: Posts: Comments:
Quoting KEEPEROFTHEGATE:
01L/TS/A/CX
MARK
23.1N/94.2W


clear for final LANDFALL near 23.5n/97.8w
Yep, looks that way. Barring last minute surprises, that outcome has saved some lives.
Member Since: Posts: Comments:
419. IKE
I remember being on here when Dolly made landfall. It wasn't that busy then either.
Member Since: Posts: Comments:
Quoting skepticall2:


What name replace Allison? Apparently us Houstonians have to watch out for it.

That would be Andrea, which was used in 2007 and will be used again in 2013.
Member Since: Posts: Comments:
Quoting Patrap:




startin' to look mighty purty right there
Member Since: Posts: Comments:
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Quoting Floodman:


one word:

Oblivious


I was thinking of a different word and I think I spelled it wrong :)

Crow-Magnon
Member Since: Posts: Comments:
Quoting HoustonTxGal:
Does anyone know what kind of surge that Galveston can expect??


Not much.
Member Since: Posts: Comments:
Yep! CROW HAS BEEN SERVED!!!!!
Member Since: Posts: Comments:
Does anyone know what kind of surge that Galveston can expect??
Member Since: Posts: Comments:
Quoting Patrap:
This Place iz kinda like New Years in a Church right now.

Empty.
there must not be many Matamoras bloggers...

BTW...anyone know what the population is there?

I haven't been there since the 80's but I remember there being alot of people living there.
Member Since: Posts: Comments:
Looks like Alex is filling up in clouds, becoming a very large category 1 storm in my opinion.
Member Since: July 1, 2008 Posts: 13 Comments: 7436
Quoting midgulfmom:
Hey Floodman...I think HoustonTxGal requested a "chicken dance" to send Africa a message to stop with the waves. ha ha ha...


Oh no! Wrong time of year for chicken dances...that simply excites the weather gods and INCREASES the problem
Member Since: Posts: Comments:



Member Since: July 3, 2005 Posts: 427 Comments: 129439
It is quiet in here now.....I guess everyone is waiting for a new storm to form.
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Brownsville will be the Ground Zero. Spots north of the hurricane usually have the worst surge, and winds. The hurricane is strongest there, so Mexico may not actually feel the strong winds or surge.
Member Since: Posts: Comments:
404. IKE
Quoting angiest:


As I recall, you were trying to welcome "junior" there for a little while. ;)

I also remember all those people going on and on about how strong storms like Ike just don't go west. No way it will hit Texas. It will recurve...



That system had classic Cape Verde storm written all over it from the start.
Member Since: Posts: Comments:
TropicalStormAlex heading toward Matamoros,Mexico/Brownsville,Texas landfall in 24hours
(Straightline projection using its last 2 positions. Take with HUGE grain of salt)

Copy&paste TAM, MOB, PBI, SAL, 22.5N92.7W, 22.7N93.1W-28.7N88.4W, 22.9N93.6W-28.7N88.4W, 23.2N94.0W-28.7N88.4W, 22.9N93.6W-23.2N94.0W, 23.2N94.0W-25.6N97.3W into the GreatCircleMapper.

The shortest red line shows the heading between the last two positions. Below the map shows:
TSAlex had a heading of 309.1degrees (~6degrees west of NorthWest), while
traveling a distance of 33miles (~53kilometres) over 3hours at a speed of 11mph (~18kph);
TSAlex's distance from DeepwaterHorizon* has remained the same;
previous closure rate was heading away at ~3mph, and at current rate of heading away at 0mph,
TSAlex remains an indefinably large number of hours away from the DeepwaterHorizon.

At 120hours away, personnel evacuations & shutdown procedures for ship evacuations begin.
(See the bottom of blog1521post705 for more info, & blog1521post3353 before obvious corrections)

* Which I've been marking as 28.7N88.4W
Member Since: Posts: Comments:
Guess being everyone pretty much knows where Alex is going they have scooted out.
Member Since: Posts: Comments:
01L/TS/A/CX
MARK
23.1N/94.2W


clear for final LANDFALL near 23.5n/97.8w
Member Since: Posts: Comments:
So Alex is moving to the WNW/NW. As expected. Those people who were saying "oh it's going to Louisana" have curiously vanished... ;)
Member Since: Posts: Comments:
This Place iz kinda like New Years Eve in a Church right now.

Empty.
Member Since: July 3, 2005 Posts: 427 Comments: 129439
Quoting TexasHurricane:


yes, I remember her...


How could any of us forget?
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Dang, everyone beat me...
Member Since: Posts: Comments:
Quoting hurricanejunky:


Your forecasts have been great! Nice work on the graphics too.


Thanks, you have a great site my friend!

Folks, check this site out@ http://weather.smartgreenhelp.com/

Sorry, I am using google chrome at the moment.
Member Since: July 1, 2008 Posts: 13 Comments: 7436
Quoting MiamiHurricanes09:
True. Could just be in the process of developing a more-defined eyewall and eye, although I doubt it. Like you said, could also be dry air intrusion although it is not signified on water vapor imagery.

Forgive my ignorance, but what altitude is water vapor measured? Or is it across all altitudes?
Member Since: Posts: Comments:

Viewing: 443 - 393

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

Local Weather

Partly Cloudy
28 °F
Partly Cloudy